LEAKAGE WATER COLLECTOR, NUCLEAR POWER PLANT AND LEAKAGE MONITORING METHOD

PROBLEM TO BE SOLVED: To reduce risks on the breakdown of a core catcher due to a delay in water injection in case of a core damage accident and those on steam explosion in case of a drop of a molten core. SOLUTION: A nuclear power plant includes a corium holding vessel 62 which is placed below a reactor vessel 1 inside a containment vessel 2 and opens upward, structures such as pedestal walls 14 forming a cooling flow channel 50 extending along outside faces to exit below the rim of the opening of the vessel, feedwater piping 12 for supplying cooling water to the cooling flow channel 50, feedwater valves 8 mounted on the feedwater piping 12, and a drain accumulation lid 5 for covering the opening. The use of the cooling flow channel 50 as a drain waste liquid sump brings the full-time existence of the cooling water in the cooling flow channel 50. COPYRIGHT: (C)2011,JPO&INPIT